Diesel Particle Filter break down

[tweak'e]

have had a quick read of most of it.

theres been quite a few assumptions made and a few that are clearly wrong.
theres no way the O2 sensor can monitor combustion or cat performance. its in the wrong place and for cat they require two.
it certainly doesn't make motor rich or lean.

the cat should be a basic cat, oxidize co and hc and convert some nox to N. as there is no O2 sensors on the cat so i doubt the ecu puts in fuel in the cat itself as it has no way of monitoring the cat.
for NOx reduction, during high EGR use there is low O2 and hig CO and HC. by the time the HC and CO have been converted there will be little O2 which enables NO reduction to take place.

O2 sensor will be just for DPF to make sure there is enough O2 to burn the fuel on regen and that it doesn't inject to much fuel during regen.

also you have to remember the role of the temp sensors. they will be checking the DPF is at operating temp. with no DPF or cat it could well be its running to cool and the ECU goes into regen mode.

 

[Old.Tony]

That's entirely possible. We haven't had an expert in DPF/CAT systems and what we've learnt in there was just from the info available, which pointed to the O2 sensor being used in conjunction with the CAT as well as the DPF.

However based on the above, it's possible the reduction in fuel consumption is purely due to no squirts done for regeneration which, in a vehicle without DPF is fine, but with a DPF would cause failure fairly quickly.

We know we HAVE to have the O2 sensor in place, because the ECU monitors its response to deliberate fluctuations in the fuel mix. But then we might just be able to remove the DPF and coat the surface of the O2 sensor with heat-proof paint and stop the squirts?

Just on the CAT operation, how would the CAT work? What would it use as a reductant, if not the hydrocarbons that make up diesel fuel?

 

[tweak'e]

Just on the CAT operation, how would the CAT work? What would it use as a reductant, if not the hydrocarbons that make up diesel fuel?

its getting late here but quickly... afaik the basic cat doesn't need HC to convert NOx to N+O, its only a certain type of cat that uses extra fuel to do that. afaik the first section of the cat converts the CO and HC, and the 2nd section coverts NO. however its only 10-20% conversion.

i understand the cat is basically like the older 2 way petrol cats.

remember the main way to reduce NOx is the EGR system, which is what produces all the CO, HC and soot the cat and DPF are cleaning up.
any NOx reduction in the cat is minor.

 

[Bosshog]

Its all too technical for me, but by trial and error I worked out that the O2 sensor position in the delete pipe was key to stopping the ECU from squirting diesel in on the exhaust stroke when the factory cat is removed. Leaving the factory cat in place means no need to relocate the O2 sensor.

 

[tweak'e]

Its all too technical for me, but by trial and error I worked out that the O2 sensor position in the delete pipe was key to stopping the ECU from squirting diesel in on the exhaust stroke when the factory cat is removed. Leaving the factory cat in place means no need to relocate the O2 sensor.

actually that sounds roughly right. the cat uses a fair bit of O2, so without the cat the oxygen sensor sees more O2 which means there is sufficient O2 for the regen, so it turns it on.
the other thing is the cat may be covering up the white smoke. white smoke is not the diesel burning but rather evaporating. the diesel is not hitting the nice hot cat and being ignited but evaporated in the exhaust pipe instead.

 

[Pedro123]

could be worse

Merchant,

I too have had the light come on, but my filter burn't itself out.

Heard a story recently about a Mazda with the same problem, don't know how true it is, but I was told the cost of the filter and labour to fix the problem was well into the thousands of $.

I'd give up having faith.. Nissan customer care doesn't!!!!!!!!!!!!!!!!!!!!

 

[Bosshog]

Merchant,

I too have had the light come on, but my filter burn't itself out.

Heard a story recently about a Mazda with the same problem, don't know how true it is, but I was told the cost of the filter and labour to fix the problem was well into the thousands of $.

I'd give up having faith.. Nissan customer care doesn't!!!!!!!!!!!!!!!!!!!!

Pedro

There are several threads and hours of reading on DPFs on here. It will keep you entertained for a long time. And yes they're expensive $4000 for a newie or $1000 for second hand one.

 

[Burmic1]

Anyone tell me does a 06 auto d40 have a dpf or only later models

 

[Old.Tony]

Your dash should tell you - I don't think the ECU would light up the DPF warning light on the dash when you first turn on the ignition. On my dash, it's just to the right of the cruise control light in the very bottom of the centre section. It should stay lit until the engine has started.

If you haven't had your vehicle since new, the previous owner may have removed the DPF, so the presence of the indicator isn't a guarantee that you have one.

Personally I'm not concerned by the presence of the DPF, but sure as chickens lay eggs I'll be ripping mine out - to save fuel.

 

[Bosshog]

Anyone tell me does a 06 auto d40 have a dpf or only later models

No it does not. Only Series 3's came with (late 2007 thru early 2010).

 

[Arty_74]

I know this probably doesn't belong in this thread but I don't believe I've heard fuel consumption figures on a TD auto pre series 3 without a DPF, would be good to compare figures with the ones that do have DPF's.
Anyone?

 

[KraftyPg]

One thing to take into account (whether you believe the DPF means bad economy or not) is that with progression comes better economy. Each new model or engine has brought better economy through new technologies and new ways of doing things so I wouldn't expect to see a much different set of figures from the earlier models than we see with the current models.

 

[Arty_74]

Hmm, I do agree that each newer model has improvements made to them, but as seen in the "D40 auto fuel economy" thread, most of us complaining about poor figures had DPF's, I believe the economy was not improved in the series 3 but made worse with the introduction of the DPF's, that is why I want to hear from the earlier TD auto owners.

 

[Pete22]

Hmm, I do agree that each newer model has improvements made to them, but as seen in the "D40 auto fuel economy" thread, most of us complaining about poor figures had DPF's, I believe the economy was not improved in the series 3 but made worse with the introduction of the DPF's, that is why I want to hear from the earlier TD auto owners.

I too have a 2008 auto STX with DPF and while I've been bitching about fuel economy you can clearly see that I've added a fair bit of extra weight so must expect some increase. Over the past couple of tanks I've been adjusting my driving style a little and driving with a close eye on the real time usage as shown by my Scangauge. I've found that, like Old Tony, I'm now getting a regular 'whole tank' economy of between 12 and 12.5 LPH.....can only hope this continues. BTW....my previous aberage was around 14 LPH.

 

[Chip Tuning]

One thing to take into account (whether you believe the DPF means bad economy or not) is that with progression comes better economy. Each new model or engine has brought better economy through new technologies and new ways of doing things so I wouldn't expect to see a much different set of figures from the earlier models than we see with the current models.

More to the point I reckon lately the last technologies have just been made for emissions control rather than ecomony. The Auto Pajero NS was way worse than the previous model because of the DPF. The NT (next model) had this system removed completely ... just like the newst model Nissan.

Truckers know this too with the introduction of that uria (add blue) liquid they need to use to stop certain emissions ... added cost to the fleets of course ... all at the customers expense!

 

[KraftyPg]

Trucks have to adhere to one of two different emission controls standards as of this year. One of them is achieved by installing EGR and in some makers cases and advanced form of EGR called Selective Catalytic Reduction (SCR) which in addition to AdBlue will lower emission, one problem being that the quantities of AdBlue needed for long haul rigs in this country means adding extra fuel tanks which of course drops chargeable load weight (or diesel capacity) but those taking this path believe the extra costs are not that substantial and worth the effort.

Those manufacturers not following the SCR method are using DPF and companies like CAT are reporting DPF's lasting 500,000 kms without the need for driver assisted regen, emissions below the 2011 requirement and fuel economy as good or better than previous models. Replacement DPF's are reco models are cost less than $500 and 4 hours off the road to fit.

Each side is talking up their own technology which is the way business works but both sides have a very viable product and while most of the AdBlue testing was done on Volvo's in Sweden the DPF tests were done on rigs doing the East/West run (Sydney to Perth) over the last 18 months (not many current trucks have the storage capacity to store enough AdBlue for the East/West run). So in some ways the DPF testing is a little truer to Australian conditions but both sides still have something to brag about.

 

[Arty_74]

I know this probably doesn't belong in this thread but I don't believe I've heard fuel consumption figures on a TD auto pre series 3 without a DPF, would be good to compare figures with the ones that do have DPF's.
Anyone?

Lol... quoting myself, still haven't heard from any auto owners pre series 3, are there any out there?

 

[KraftyPg]

You might have to look through the D40 economy thread or the general economy thread I'm sure you will find all series D40's and their economy, it might take extra work on your behalf by comparing the years to the series but with as many people as there are in this site I'm sure the answers have to be there somewhere.

 

[Chip Tuning]

... companies like CAT are reporting DPF's lasting 500,000 kms without the need for driver assisted regen

HA. What is DRIVER ASSISTED REGEN??? Toothbrush and cleaning fluid on the side of the road?

Krafty they have a bit of a play with words since NO DPF regen requires driver assistance as driving the vehicle without stopping is whats needed.

Replacement DPF's are reco models are cost less than $500 and 4 hours off the road to fit.

I would like to see this come true. Mitsu and Nissan charge $3000 for their replacement DPFs

 

[KraftyPg]

Driver assisted being without the driver having to slow down and keep the revs up, a method D40's can do under some circumstances, or where the driver has to stop and keep the revs up like required by Toyota's. Anything automatic happens essentially without the driver knowing or having to do anything. Play with the words how you want CAT have done 500,000ks with a DPF fitted vehicle and the driver hasn't been effected by any of the regen cycles.

As for the price coming true, sure we'd all like to see it in Nissan's and Mitus's but there is many factors as to why it wont and as my quoted figures were related to a CAT engine not a toy truck engine it's not really comparative.